Need 3rd brake help - ZR-1 Net Registry Forums

xlr8nflorida · 11-06-2010

Went to a show today - told my third brake light not working.
One of the ncrs guys said it's a switch under passenger dash.

How do I troubleshoot it, I'd like to get my third brake light back?

Thanks for help in advance

tomtom72 · 11-06-2010

okay Jim, not to leave you hanging....the brake light switch controls both the tail lamp brake lights and the CHMSL....I assume that since the CHMSL gets it's power on a seperate circuit from the low stop lamps that I'll look in 8A and report back. You checked the fuse block right? Not trying to be funny.

For now I'd try to wedge the brake pedal and then check for power at the CHMSL wiring. I assume that the brake light switch is on the top of the brake pedal...but you didn't say that the other stop lights were out so I doubt that is the trouble....but I'll look in 8A....god I hate these electrical gremlins!

Tom

Toyvet1 · 11-06-2010

Had the same problem about a year ago, replaced the brake light switch and problem solved. About $10 at Advance auto.

xlr8nflorida · 11-07-2010

Quote:

Originally Posted by Toyvet1

Had the same problem about a year ago, replaced the brake light switch and problem solved. About $10 at Advance auto.

Thank you tom and toy vet.

My brake lights work just not the 3rd brake light.

Can you give me part numbers and also instructions?

Part number for gm and advance part number plus price - probably pfer gm part

Guy told me today it's 2 hour job is that correct?

Ps I have not checked fuse block, which fuse do I look at and I'm checking for blown fuse?

ScottZ95ZR1 · 11-07-2010

AC Delco 852A - GM 25529860

http://cgi.ebay.com/ebaymotors/AC-DE...item4cf0bf2958

Toyvet1 · 11-07-2010

Switch is easy to replace. Remove hush panel . I belive you can get to the switch without removing the metal support behind hush panel. Then just pull the switch out of its holder. Undo the wiring and reassemble evertyhing. Shouldnt take more than 30 or 40 minutes.

Z51JEFF · 11-07-2010

Quote:

Originally Posted by xlr8nflorida

One of the ncrs guys said it's a switch under passenger dash.

Hope this isnt one of the guys writing specs on C4 judging but Im not an NCRS fan,just might make it a little harder on some.The switch is the most common cause of the second light not working.I replaced mine and I do remember having the metal support out once but cant remember why,dont know if this has to come out or not.As stated it might take 30 minutes +.

jrd1990zr1 · 11-07-2010

Common problem on C-4s. I had to replace one on my 86 and one on my 90 Z. There are actually two circuits to the brake light switch, that is why the main brake lights still work. If you have a tendency to take your foot off the brake quickly (like we all do) the switch pops ever so slightly out of it's mount, so the petal does not make contact.

When you pull the hush panel reach under and you might be able to push the switch back into position so it works at least temporarily.

You will need to replace it long term since the plastic ridges on the switch get rounded over by the metal holder over time. Hope I explained it well enough!

If you look up using a mirror you will see what I mean. It's a real PITA unless you have long arms.

jrd1990zr1 · 11-07-2010

Quote:

Originally Posted by Z51JEFF

Hope this isnt one of the guys writing specs on C4 judging but Im not an NCRS fan,just might make it a little harder on some.The switch is the most common cause of the second light not working.I replaced mine and I do remember having the metal support out once but cant remember why,dont know if this has to come out or not.As stated it might take 30 minutes +.

Jeff,

The hush panel conceals the switch so a replacement switch would not be detected. If the high level light did not function it would be a point deduction in the operations section during NCRS judging.

John

Z51JEFF · 11-09-2010

Quote:

Originally Posted by jrd1990zr1

Jeff,

The hush panel conceals the switch so a replacement switch would not be detected. If the high level light did not function it would be a point deduction in the operations section during NCRS judging.

John

My point being the guy stated the switch is on the right side of the car.

11-06-2010	#1
xlr8nflorida Join Date: May 2008 Location: USA Posts: 1,095	Need 3rd brake help Went to a show today - told my third brake light not working. One of the ncrs guys said it's a switch under passenger dash. How do I troubleshoot it, I'd like to get my third brake light back? Thanks for help in advance

11-06-2010	#2
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,637	Re: Need 3rd brake help okay Jim, not to leave you hanging....the brake light switch controls both the tail lamp brake lights and the CHMSL....I assume that since the CHMSL gets it's power on a seperate circuit from the low stop lamps that I'll look in 8A and report back. You checked the fuse block right? Not trying to be funny. For now I'd try to wedge the brake pedal and then check for power at the CHMSL wiring. I assume that the brake light switch is on the top of the brake pedal...but you didn't say that the other stop lights were out so I doubt that is the trouble....but I'll look in 8A....god I hate these electrical gremlins! Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

11-06-2010	#3
Toyvet1 Join Date: Dec 2007 Location: Bloomingdale, Il Posts: 330	Re: Need 3rd brake help Had the same problem about a year ago, replaced the brake light switch and problem solved. About $10 at Advance auto.

11-07-2010	#5
ScottZ95ZR1 Join Date: Mar 2008 Location: Pendleton, IN Posts: 668	Re: Need 3rd brake help AC Delco 852A - GM 25529860 http://cgi.ebay.com/ebaymotors/AC-DE...item4cf0bf2958

11-07-2010	#6
Toyvet1 Join Date: Dec 2007 Location: Bloomingdale, Il Posts: 330	Re: Need 3rd brake help Switch is easy to replace. Remove hush panel . I belive you can get to the switch without removing the metal support behind hush panel. Then just pull the switch out of its holder. Undo the wiring and reassemble evertyhing. Shouldnt take more than 30 or 40 minutes.

11-07-2010	#8
jrd1990zr1 Join Date: Dec 2005 Location: Delanson, NY Posts: 931	Re: Need 3rd brake help Common problem on C-4s. I had to replace one on my 86 and one on my 90 Z. There are actually two circuits to the brake light switch, that is why the main brake lights still work. If you have a tendency to take your foot off the brake quickly (like we all do) the switch pops ever so slightly out of it's mount, so the petal does not make contact. When you pull the hush panel reach under and you might be able to push the switch back into position so it works at least temporarily. You will need to replace it long term since the plastic ridges on the switch get rounded over by the metal holder over time. Hope I explained it well enough! If you look up using a mirror you will see what I mean. It's a real PITA unless you have long arms.